Using task manager is fine solution for real time checking in. The only issue I have is the real time graph changes scale depending on the current bandwidth being used so sometimes it's not convenient for a quick glance at the remaining amount. Additionally, it requires you to keep task manager open. For me, I use task manager for quick glances but use FreeMeter for long term monitoring by keeping it open in the background. It's nice too being you can customize the scales, refresh rates, colors of uploaded/download, and many other options.